During performance of a construction project, it is often necessary to determine the actual elevation of an underground feature. For example, subsequent to completion of an underground sewer system, it is often necessary to determine the actual elevation of features such as underground flow lines and the like relative to the elevation of such features called for in the engineering drawings. These actual measurements, generally referred to as “as built measurements,” or simply “as builts,” are useful for future planning since the actual elevations of underground structures often vary, in some cases significantly, from their planned locations. Moreover, in the case of an underground sewer system, “as built measurements” are used to confirm that the various pipe sections of the sewer system are orientated at a proper elevation relative to one another to ensure that waste water flows in the proper direction through the sewer system.
The procurement of “as built measurements” is often difficult. The elevation of the structure being measured is often difficult to determine without physically accessing the structure. For example, in the case of a sewer system, it is difficult to obtain the elevation measurement of the end of a pipe without physically climbing into the sewer to obtain the measurement.